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Array Variable initialization

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  • T toxcct

    can you show your constructor please ?

    T.RATHA KRISHNAN wrote:

    TModels[1](0);

    this line makes absolutely no sense, and i don't even know what you're trying to achieve with this. BTW, can't you just use the STL ans its containers ?

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    T RATHA KRISHNAN
    wrote on last edited by
    #3

    Thanks. I've corrected this error myself.

    T 1 Reply Last reply
    0
    • T T RATHA KRISHNAN

      Thanks. I've corrected this error myself.

      T Offline
      T Offline
      toxcct
      wrote on last edited by
      #4

      and for the benefit of everyone, will you share this with us ?

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      • T T RATHA KRISHNAN

        Hi! I've initialized an Array element in the Constructor. But it shows syntax error. TModels[1](0); The error is: error C2059: syntax error : '[' How to initialize an array element in the Constructor?

        L Offline
        L Offline
        laksh2204
        wrote on last edited by
        #5

        I think you are trying to do something like this.. class A{ int TModels[3]; public: A():TModels[1](0){} }; int main(){ A a; } which is giving you above error: As per my knowledge there is no (standard) C++ way of doing this. Array initializers do not exist for classes. So prob you can do it somewhat like this: class A{ int TModels[3]; public: A(){ for(int i=0; i<3; i++) TModels[i] = 0; } }; int main(){ A a; } Hope it helps you

        T 1 Reply Last reply
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        • T toxcct

          and for the benefit of everyone, will you share this with us ?

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          T Offline
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          T RATHA KRISHNAN
          wrote on last edited by
          #6

          Oh! With Pleasure! First I initialized the array elements like this:

          TestAI::TestAI() //Constructor
          TModels[1](0)
          , TModels[2](0)
          , TModels[3](0)
          {

          }

          and now I change it to the following:

          TestAI::TestAI() //Constructor
          {
          TModels[1] = 0;
          TModels[2] = 0;
          TModels[3] = 0;

          }

          and the errors vanished.

          T 1 Reply Last reply
          0
          • L laksh2204

            I think you are trying to do something like this.. class A{ int TModels[3]; public: A():TModels[1](0){} }; int main(){ A a; } which is giving you above error: As per my knowledge there is no (standard) C++ way of doing this. Array initializers do not exist for classes. So prob you can do it somewhat like this: class A{ int TModels[3]; public: A(){ for(int i=0; i<3; i++) TModels[i] = 0; } }; int main(){ A a; } Hope it helps you

            T Offline
            T Offline
            T RATHA KRISHNAN
            wrote on last edited by
            #7

            Thanks. I've already corrected that.

            1 Reply Last reply
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            • T T RATHA KRISHNAN

              Oh! With Pleasure! First I initialized the array elements like this:

              TestAI::TestAI() //Constructor
              TModels[1](0)
              , TModels[2](0)
              , TModels[3](0)
              {

              }

              and now I change it to the following:

              TestAI::TestAI() //Constructor
              {
              TModels[1] = 0;
              TModels[2] = 0;
              TModels[3] = 0;

              }

              and the errors vanished.

              T Offline
              T Offline
              toxcct
              wrote on last edited by
              #8

              why don't you just do this :

              TModel = {0};

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              • T toxcct

                why don't you just do this :

                TModel = {0};

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                C Offline
                C Offline
                CPallini
                wrote on last edited by
                #9

                Because it doesn't work? For instance

                int a[50] = {0};

                Doesn't produce the result I'm expecting (it initializes only the first array element). Am i wrong? :)

                If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                [My articles]

                T D 2 Replies Last reply
                0
                • C CPallini

                  Because it doesn't work? For instance

                  int a[50] = {0};

                  Doesn't produce the result I'm expecting (it initializes only the first array element). Am i wrong? :)

                  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                  This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                  [My articles]

                  T Offline
                  T Offline
                  toxcct
                  wrote on last edited by
                  #10

                  CPallini wrote:

                  Am i wrong?

                  you are, or the compiler is ! the standard says that such a construction (when initializing a variable at the same time than declaration) initializes every element of the array to their default value. I'm even pretty sure Nemanja Trifunovic quoted me somewhere about that...

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                  C 1 Reply Last reply
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                  • C CPallini

                    Because it doesn't work? For instance

                    int a[50] = {0};

                    Doesn't produce the result I'm expecting (it initializes only the first array element). Am i wrong? :)

                    If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                    [My articles]

                    D Offline
                    D Offline
                    David Crow
                    wrote on last edited by
                    #11

                    CPallini wrote:

                    (it initializes only the first array element).

                    Not according to the STOSx instructions. Of course, I only use it to initialize POD types to 0. Otherwise, I'd use memset().

                    "Love people and use things, not love things and use people." - Unknown

                    "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                    C 1 Reply Last reply
                    0
                    • T toxcct

                      CPallini wrote:

                      Am i wrong?

                      you are, or the compiler is ! the standard says that such a construction (when initializing a variable at the same time than declaration) initializes every element of the array to their default value. I'm even pretty sure Nemanja Trifunovic quoted me somewhere about that...

                      [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

                      C Offline
                      C Offline
                      CPallini
                      wrote on last edited by
                      #12

                      toxcct wrote:

                      you are, or the compiler is !

                      Maybe the latter: the program:

                      #include <iostream>
                      using namespace std;

                      void main()
                      {
                      const int N = 10;
                      int a[N]={7};

                      for (int i=0; i<N;i++)
                      {
                      cout << a[i] << endl;
                      }
                      }

                      the output:

                      7
                      0
                      0
                      0
                      0
                      0
                      0
                      0
                      0
                      0

                      The system: Visual C++ 2008 Express Edition running on Win XP. Eventually YOU may be wrong! ;P (actually I'm quite confident you're right, but don't use it unless you really want surprises!) [added] Actually I think VS2008 cannot be so out-of-the-standard. I suppose the standard establishing that, whenever the initialization list is too short, the remaining array items are default-initialized (to 0 if integers). [/added] :)

                      If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                      This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                      [My articles]

                      modified on Tuesday, September 9, 2008 11:53 AM

                      S 1 Reply Last reply
                      0
                      • D David Crow

                        CPallini wrote:

                        (it initializes only the first array element).

                        Not according to the STOSx instructions. Of course, I only use it to initialize POD types to 0. Otherwise, I'd use memset().

                        "Love people and use things, not love things and use people." - Unknown

                        "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                        C Offline
                        C Offline
                        CPallini
                        wrote on last edited by
                        #13

                        Sorry no STOS here:

                        ...
                        const int N = 10;
                        int a[N]={7};
                        00401003 xor eax,eax
                        00401005 push esi
                        00401006 mov dword ptr [esp+8],7
                        0040100E mov dword ptr [esp+0Ch],eax
                        00401012 mov dword ptr [esp+10h],eax
                        00401016 mov dword ptr [esp+14h],eax
                        0040101A mov dword ptr [esp+18h],eax
                        0040101E mov dword ptr [esp+1Ch],eax
                        00401022 mov dword ptr [esp+20h],eax
                        00401026 mov dword ptr [esp+24h],eax
                        0040102A mov dword ptr [esp+28h],eax
                        0040102E mov dword ptr [esp+2Ch],eax
                        ...

                        (Visual C++ 2008 Express Edition, Win XP). :)

                        If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                        [My articles]

                        D 1 Reply Last reply
                        0
                        • C CPallini

                          toxcct wrote:

                          you are, or the compiler is !

                          Maybe the latter: the program:

                          #include <iostream>
                          using namespace std;

                          void main()
                          {
                          const int N = 10;
                          int a[N]={7};

                          for (int i=0; i<N;i++)
                          {
                          cout << a[i] << endl;
                          }
                          }

                          the output:

                          7
                          0
                          0
                          0
                          0
                          0
                          0
                          0
                          0
                          0

                          The system: Visual C++ 2008 Express Edition running on Win XP. Eventually YOU may be wrong! ;P (actually I'm quite confident you're right, but don't use it unless you really want surprises!) [added] Actually I think VS2008 cannot be so out-of-the-standard. I suppose the standard establishing that, whenever the initialization list is too short, the remaining array items are default-initialized (to 0 if integers). [/added] :)

                          If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                          This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                          [My articles]

                          modified on Tuesday, September 9, 2008 11:53 AM

                          S Offline
                          S Offline
                          SandipG
                          wrote on last edited by
                          #14

                          Same output with Visual C++ 6.0, WinXP SP2 :) Surprising..:confused:

                          Regards, Sandip.

                          T 1 Reply Last reply
                          0
                          • C CPallini

                            Sorry no STOS here:

                            ...
                            const int N = 10;
                            int a[N]={7};
                            00401003 xor eax,eax
                            00401005 push esi
                            00401006 mov dword ptr [esp+8],7
                            0040100E mov dword ptr [esp+0Ch],eax
                            00401012 mov dword ptr [esp+10h],eax
                            00401016 mov dword ptr [esp+14h],eax
                            0040101A mov dword ptr [esp+18h],eax
                            0040101E mov dword ptr [esp+1Ch],eax
                            00401022 mov dword ptr [esp+20h],eax
                            00401026 mov dword ptr [esp+24h],eax
                            0040102A mov dword ptr [esp+28h],eax
                            0040102E mov dword ptr [esp+2Ch],eax
                            ...

                            (Visual C++ 2008 Express Edition, Win XP). :)

                            If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                            This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                            [My articles]

                            D Offline
                            D Offline
                            David Crow
                            wrote on last edited by
                            #15

                            CPallini wrote:

                            00401003 xor eax,eax

                            Look two lines up from this one and you should find:

                            rep stosd

                            "Love people and use things, not love things and use people." - Unknown

                            "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                            C 1 Reply Last reply
                            0
                            • D David Crow

                              CPallini wrote:

                              00401003 xor eax,eax

                              Look two lines up from this one and you should find:

                              rep stosd

                              "Love people and use things, not love things and use people." - Unknown

                              "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                              C Offline
                              C Offline
                              CPallini
                              wrote on last edited by
                              #16

                              No luck (there isn't such insruction). On the other hand, the output of this program [^] confirms my assumption. See also Sandip's post [^]. I should admit I was very surprised by such a behaviour. :)

                              If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                              This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                              [My articles]

                              T 1 Reply Last reply
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                              • S SandipG

                                Same output with Visual C++ 6.0, WinXP SP2 :) Surprising..:confused:

                                Regards, Sandip.

                                T Offline
                                T Offline
                                toxcct
                                wrote on last edited by
                                #17

                                SandipG :) wrote:

                                Same output with Visual C++ 6.0

                                Visual C++ is not what a decent programmer call a standard compliant compiler, Sir !

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                                C 1 Reply Last reply
                                0
                                • C CPallini

                                  No luck (there isn't such insruction). On the other hand, the output of this program [^] confirms my assumption. See also Sandip's post [^]. I should admit I was very surprised by such a behaviour. :)

                                  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                                  This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                                  [My articles]

                                  T Offline
                                  T Offline
                                  toxcct
                                  wrote on last edited by
                                  #18

                                  and what about {0} instead of {7}, and in Release Mode, not in Debug Mode ?

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                                  • T toxcct

                                    and what about {0} instead of {7}, and in Release Mode, not in Debug Mode ?

                                    [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

                                    C Offline
                                    C Offline
                                    CPallini
                                    wrote on last edited by
                                    #19

                                    See my added remark here [^]. BTW my tests were of course performed both in Debug and the Release mode. ;P :)

                                    If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                                    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                                    [My articles]

                                    1 Reply Last reply
                                    0
                                    • T toxcct

                                      and what about {0} instead of {7}, and in Release Mode, not in Debug Mode ?

                                      [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

                                      D Offline
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                                      David Crow
                                      wrote on last edited by
                                      #20

                                      toxcct wrote:

                                      ...and what about {0} instead of {7}...

                                      0 works fine.

                                      toxcct wrote:

                                      ...and in Release Mode, not in Debug Mode ?

                                      Same results for both 0 and 7. This is why I only do it when setting things to 0. I use memset() otherwise.

                                      "Love people and use things, not love things and use people." - Unknown

                                      "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                                      C 1 Reply Last reply
                                      0
                                      • T toxcct

                                        SandipG :) wrote:

                                        Same output with Visual C++ 6.0

                                        Visual C++ is not what a decent programmer call a standard compliant compiler, Sir !

                                        [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

                                        C Offline
                                        C Offline
                                        CPallini
                                        wrote on last edited by
                                        #21

                                        IMHO such a discrepancy would be too gross, even for VC6. :)

                                        If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                                        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                                        [My articles]

                                        T 1 Reply Last reply
                                        0
                                        • C CPallini

                                          IMHO such a discrepancy would be too gross, even for VC6. :)

                                          If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                                          This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                                          [My articles]

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                                          T Offline
                                          toxcct
                                          wrote on last edited by
                                          #22

                                          yes, probably, but it's not *THE* compiler to test the standard ! ;) ;P

                                          [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

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